The invention relates to cloned DNA sequences analogous to the genomic RNA of a virus known as Lymphadenopathy-Associated Virus II (xe2x80x9cLAV-IIxe2x80x9d), a process for the preparation of these cloned DNA sequences, and their use as probes in diagnostic kits. In one embodiment, the invention relates to a cloned DNA sequence analogous to the entire genomic RNA of HIV-2 and its use as a probe. The invention also relates to polypeptides with amino acid sequences encoded by these cloned DNA sequences and the use of these polypeptides in diagnostic kits.
According to recently adopted nomenclature, as reported in Nature, May 1986, a substantially-identical group of retroviruses which has been identified as one causative agent of AIDS are now referred to as Human Immunodeficiency Viruses I (HIV-1). This previously-described group of retroviruses includes Lymphadenopathy-Associated Virus I (LAV-I), Human T-cell Lymphotropic Virus-III (HTLV-III), and AIDS-Related Virus (ARV).
Lymphadenopathy-Associated Virus II has been described in U.S. application Ser. No. 835,228, which was filed Mar. 3, 1986, and is specifically incorporated herein by reference. Because LAV-II is a second, distinct causative agent of AIDS, LAV-II properly is classifiable as a Human Immunodeficiency Virus II (HIV-2). Therefore, xe2x80x9cLAV-IIxe2x80x9d as used hereinafter describes a particular genus of HIV-2 isolates.
While HIV-2 is related to HIV-1 by its morphology, its tropism and its in vitro cytopathic effect on CD4 (T4) positive cell lines and lymphocytes, HIV-2 differs from previously described human retroviruses known to be responsible for AIDS. Moreover, the proteins of HIV-1 and 2 have different sizes and their serological cross-reactivity is restricted mostly to the major core protein, as the envelope glycoproteins of HIV-2 are not immune precipitated by HIV-1-positive sera except in some cases where very faint cross-reactivity can be detected. Since a significant proportion of the HIV infected patients lack antibodies to the major core protein of their infecting virus, it is important to include antigens to both HIV-1 and HIV-2 in an effective serum test for the diagnosis of the infection by these viruses.
HIV-2 was first discovered in the course of serological research on patients native to Guinea-Bissau who exhibited clinical and immunological symptoms of AIDS and from whom sero-negative or weakly sero-positive reactions to tests using an HIV-1 lysate were obtained. Further clinical studies on these patients isolated viruses which were subsequently named xe2x80x9cLAV-II.xe2x80x9d
One LAV-II isolate, subsequently referred to as LAV-II MIR, was deposited at the Collection Nationale des Cultures de Micro-Organismes (CNCM) at the Institut Pasteur in Paris, France on Dec. 19, 1985 under Accession No. I-502 nd has also been deposited at the British ECA CC under No. 87.001.001 on Jan. 9, 1987. A second LAV-II isolate was deposited at CNCM on Feb. 21, 1986 under Accession No. I-532 and has also been deposited at the British ECA CC under No. 87.001.002 on Jan. 9, 1987. This second isolate has been subsequently referred to as LAV-II ROD. Other isolates deposited at the CNCM on Dec. 19, 1986 are HIV-2 IRMO (No. I-642) and HIV-2 EHO (No. I-643). Several additional isolates have been obtained from West African patients, some of whom have AIDS, others with AIDS-related conditions and others with no AIDS symptoms. All of these viruses have been isolated on normal human lymphocyte cultures and some of them were thereafter propagated on lymphoid tumor cell lines such as CEM and MOLT.
Due to the sero-negative or weak sero-positive results obtained when using kits designed to identify HIV-1 infections in the diagnosis of these new patients with HIV-2 disease, it has been necessary to devise a new diagnostic kit capable of detecting HIV-2 infection, either by itself or in combination with an HIV-1 infection. The present inventors have, through the development of cloned DNA sequences analogous to at least a portion of the genomic RNA of LAV-II ROD viruses, created the materials necessary for the development of such kits.
As noted previously, the present invention relates to the cloned nucleotide sequences homologous or identical to at least a portion of the genomic RNA of HIV-2 viruses and to polypeptides encoded by the same. The present invention also relates to kits capable of diagnosing an HIV-2 infection.
Thus, a main object of the present invention is to provide a kit capable of diagnosing an infection caused by the HIV-2 virus. This kit may operate by detecting at least a portion of the RNA genome of the HIV-2 virus or the provirus present in the infected cells through hybridization with a DNA probe or it may operate through the immunodiagnostic detection of polypeptides unique to the HIV-2 virus.
Additional objects and advantages of the present invention will be set forth in part in the description which follows, or may be learned from practice of the invention. The objects and advantages may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.
To achieve these objects and in accordance with the purposes of the present invention, cloned DNA sequences related to the entire genomic RNA of the LAV-II virus are set forth. These sequences are analogous specifically to the entire genome of the LAV-II ROD strain.
To further achieve the objects and in accordance with the purposes of the present invention, a kit capable of diagnosing an HIV-2 infection is described. This kit, in one embodiment, contains the cloned DNA sequences of this invention which are capable of hybridizing to viral RNA or analogous DNA sequences to indicate the presence of an HIV-2 infection. Different diagnostic techniques can be used which include, but are not limited to: (1) Southern blot procedures to identify cellular DNA which may or may not be digested with restriction enzymes; (2) Northern blot techniques to identify RNA extracted from cells; and (3) dot blot techniques, i.e., direct filtration of the sample through an ad hoc membrane such as nitrocellulose or nylon without previous separation on agarose gel. Suitable material for dot blot technique could be obtained from body fluids including, but not limited to, serum and plasma, supernatants from culture cells, or cytoplasmic extracts obtained after cell lysis and removal of membranes and nuclei of the cells by centrifugation as accomplished in the xe2x80x9cCYTODOTxe2x80x9d procedure as described in a booklet published by Schleicher and Schull.
In an alternate embodiment, the kit contains the poly-peptides created using these cloned DNA sequences. These poly-peptides are capable of reacting with antibodies to the HIV-2 virus present in sera of infected individuals, thus yielding an immunodiagnostic complex.
It is understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as claimed. The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate one embodiment of the invention and, together with the description, serve to explain the principles of the invention.